The invention is directed to a compact device for generating alternating current using solar energy.
Present solar generators employ photovoltaic cells that are connected to generate direct current (DC) electricity. For example, U.S. Pat. No. 4,614,879 describes a photovoltaic panel for converting solar energy into electrical energy output having a desired voltage and current and which is connected to a load. Typically, as described in U.S. Pat. No. 4,321,416 solar generator systems comprise an array of photovoltaic cells or modules that are connected in particular series-parallel circuited arrangements to achieved the desired outputs. The DC output can be converted into alternating current (AC) by passing the DC through an inverter such as in the apparatus described in U.S. Pat. No. 4,217,633. Other AC solar generators employ pairs of PN junction solar cells that are connected in antiparallel and a means for directing light alternatively to the PN junctions. (See U.S. Pat. No. 4,577,052.)
Despite the many advances in AC solar generators such prior art systems exhibit a number of limitations. For one thing, a typical panel produces only approximately 5 to 6 watts per square foot of coverage, which means that extensive surface areas are required to generate enough power for many applications. In addition, standard DC electrical outputs cannot be transformed and therefore cannot be transmitted long distances from the place of generation. Rather, the DC output must first be converted to AC before being put through a transformer to be transported long distances or to be put into the existing electric grid. Finally, a photovoltaic cell""s energy generating capacity depends on its orientation to the sun.
The present invention is directed to a portable device that generates AC electric energy. The device includes a plurality of solar panels that are attached to vanes that are mounted on a rotating shaft that is actuated by a DC motor. As the panels rotate a fluctuating, or alternating, voltage is developed. The output voltage and current vary in a sinusoidal waveform of the light intensity incident on each panel. Specifically, by rotating each vane, the intensity of incident radiation on the panel varies sinusoidally, thereby developing a sinusoidal electrical voltage and current output.